Facebook OpenGraph error

Hi, I use Jetpack plugin with publicize module activated for Facebook.
The problem is for some time when I create a new article the thumbnail that appears on Facebook is same at every article. I performed an exact analysis with Facebook Open Graph Object Debugger and I have the following error:
og:image could not be downloaded or is too small: Provided og:image could not be downloaded or is not big enough. Please use an image that’s at least 200x200px and is accessible from Facebook. Image ‘http://elitegamers.r…ess-630×355.jpg’ will be used instead.
The image that i use is bigger than 200x200px, so I suppose this would not be the problem.
Thanks!

https://wordpress.org/plugins/jetpack/